Importing Custom Ability Panics Compile

[benplotke]

Steps to Reproduce

1. Create SortAbility.roc with contents:

module [
    Comparison,
    Sort,
]

Comparison : [LessThan, Equal, GreaterThan]
Sort implements
    compare : a, a -> Comparison where a implements Sort

2. In the same directory, create ImportAbility.roc with contents:

module [
]

import SortAbility

3. run roc test AbilityImport.roc

Expected Results

Nothing

Actual

 ~/docs/code/roc/OrderedCollections $ ~/roc/roc_ben-build-2024-05-02-798dd77/roc test AbilityImport.roc
An internal compiler expectation was broken.
This is definitely a compiler bug.
Please file an issue here: https://github.com/roc-lang/roc/issues/new/choose
thread '<unnamed>' panicked at crates/compiler/load_internal/src/file.rs:4535:29:
Import ability member `SortAbility.compare` not available
stack backtrace:
   0: rust_begin_unwind
             at /rustc/cc66ad468955717ab92600c770da8c1601a4ff33/library/std/src/panicking.rs:595:5
   1: core::panicking::panic_fmt
             at /rustc/cc66ad468955717ab92600c770da8c1601a4ff33/library/core/src/panicking.rs:67:14
   2: import_variable_for_symbol
             at /home/ben/roc/roc-src/crates/compiler/load_internal/src/file.rs:4535:29
   3: roc_load_internal::file::add_imports::{{closure}}
             at /home/ben/roc/roc-src/crates/compiler/load_internal/src/file.rs:4429:17
   4: roc_can::abilities::IAbilitiesStore<roc_can::abilities::Pending>::resolve_for_module::{{closure}}
             at /home/ben/roc/roc-src/crates/compiler/can/src/abilities.rs:621:44
   5: core::iter::adapters::map::map_fold::{{closure}}
             at /rustc/cc66ad468955717ab92600c770da8c1601a4ff33/library/core/src/iter/adapters/map.rs:84:28
   6: core::iter::traits::iterator::Iterator::fold
             at /rustc/cc66ad468955717ab92600c770da8c1601a4ff33/library/core/src/iter/traits/iterator.rs:2639:21
   7: fold<(roc_module::symbol::Symbol, roc_can::abilities::AbilityMemberData<roc_can::abilities::Resolved>), std::collections::hash::map::IntoIter<roc_module::symbol::Symbol, roc_can::abilities::AbilityMemberData<roc_can::abilities::Pending>>, roc_can::abilities::{impl#7}::resolve_for_module::{closure_env#0}<roc_load_internal::file::add_imports::Ctx, roc_load_internal::file::add_imports::{closure_env#0}, roc_load_internal::file::add_imports::{closure_env#1}>, (), core::iter::traits::iterator::Iterator::for_each::call::{closure_env#0}<(roc_module::symbol::Symbol, roc_can::abilities::AbilityMemberData<roc_can::abilities::Resolved>), hashbrown::map::{impl#95}::extend::{closure_env#0}<roc_module::symbol::Symbol, roc_can::abilities::AbilityMemberData<roc_can::abilities::Resolved>, core::hash::BuildHasherDefault<wyhash::traits::WyHash>, alloc::alloc::Global, core::iter::adapters::map::Map<std::collections::hash::map::IntoIter<roc_module::symbol::Symbol, roc_can::abilities::AbilityMemberData<roc_can::abilities::Pending>>, roc_can::abilities::{impl#7}::resolve_for_module::{closure_env#0}<roc_load_internal::file::add_imports::Ctx, roc_load_internal::file::add_imports::{closure_env#0}, roc_load_internal::file::add_imports::{closure_env#1}>>>>>
             at /rustc/cc66ad468955717ab92600c770da8c1601a4ff33/library/core/src/iter/adapters/map.rs:124:9
   8: for_each<core::iter::adapters::map::Map<std::collections::hash::map::IntoIter<roc_module::symbol::Symbol, roc_can::abilities::AbilityMemberData<roc_can::abilities::Pending>>, roc_can::abilities::{impl#7}::resolve_for_module::{closure_env#0}<roc_load_internal::file::add_imports::Ctx, roc_load_internal::file::add_imports::{closure_env#0}, roc_load_internal::file::add_imports::{closure_env#1}>>, hashbrown::map::{impl#95}::extend::{closure_env#0}<roc_module::symbol::Symbol, roc_can::abilities::AbilityMemberData<roc_can::abilities::Resolved>, core::hash::BuildHasherDefault<wyhash::traits::WyHash>, alloc::alloc::Global, core::iter::adapters::map::Map<std::collections::hash::map::IntoIter<roc_module::symbol::Symbol, roc_can::abilities::AbilityMemberData<roc_can::abilities::Pending>>, roc_can::abilities::{impl#7}::resolve_for_module::{closure_env#0}<roc_load_internal::file::add_imports::Ctx, roc_load_internal::file::add_imports::{closure_env#0}, roc_load_internal::file::add_imports::{closure_env#1}>>>>
             at /rustc/cc66ad468955717ab92600c770da8c1601a4ff33/library/core/src/iter/traits/iterator.rs:857:9
   9: extend<roc_module::symbol::Symbol, roc_can::abilities::AbilityMemberData<roc_can::abilities::Resolved>, core::hash::BuildHasherDefault<wyhash::traits::WyHash>, alloc::alloc::Global, core::iter::adapters::map::Map<std::collections::hash::map::IntoIter<roc_module::symbol::Symbol, roc_can::abilities::AbilityMemberData<roc_can::abilities::Pending>>, roc_can::abilities::{impl#7}::resolve_for_module::{closure_env#0}<roc_load_internal::file::add_imports::Ctx, roc_load_internal::file::add_imports::{closure_env#0}, roc_load_internal::file::add_imports::{closure_env#1}>>>
             at /cargo/registry/src/index.crates.io-6f17d22bba15001f/hashbrown-0.14.0/src/map.rs:6455:9
  10: extend<roc_module::symbol::Symbol, roc_can::abilities::AbilityMemberData<roc_can::abilities::Resolved>, core::hash::BuildHasherDefault<wyhash::traits::WyHash>, core::iter::adapters::map::Map<std::collections::hash::map::IntoIter<roc_module::symbol::Symbol, roc_can::abilities::AbilityMemberData<roc_can::abilities::Pending>>, roc_can::abilities::{impl#7}::resolve_for_module::{closure_env#0}<roc_load_internal::file::add_imports::Ctx, roc_load_internal::file::add_imports::{closure_env#0}, roc_load_internal::file::add_imports::{closure_env#1}>>>
             at /rustc/cc66ad468955717ab92600c770da8c1601a4ff33/library/std/src/collections/hash/map.rs:3038:9
  11: from_iter<roc_module::symbol::Symbol, roc_can::abilities::AbilityMemberData<roc_can::abilities::Resolved>, core::hash::BuildHasherDefault<wyhash::traits::WyHash>, core::iter::adapters::map::Map<std::collections::hash::map::IntoIter<roc_module::symbol::Symbol, roc_can::abilities::AbilityMemberData<roc_can::abilities::Pending>>, roc_can::abilities::{impl#7}::resolve_for_module::{closure_env#0}<roc_load_internal::file::add_imports::Ctx, roc_load_internal::file::add_imports::{closure_env#0}, roc_load_internal::file::add_imports::{closure_env#1}>>>
             at /rustc/cc66ad468955717ab92600c770da8c1601a4ff33/library/std/src/collections/hash/map.rs:3023:13
  12: core::iter::traits::iterator::Iterator::collect
             at /rustc/cc66ad468955717ab92600c770da8c1601a4ff33/library/core/src/iter/traits/iterator.rs:2053:9
  13: roc_can::abilities::IAbilitiesStore<roc_can::abilities::Pending>::resolve_for_module
             at /home/ben/roc/roc-src/crates/compiler/can/src/abilities.rs:605:31
  14: add_imports
             at /home/ben/roc/roc-src/crates/compiler/load_internal/src/file.rs:4417:27
  15: run_solve_solve
             at /home/ben/roc/roc-src/crates/compiler/load_internal/src/file.rs:4604:47
  16: roc_load_internal::file::run_solve
             at /home/ben/roc/roc-src/crates/compiler/load_internal/src/file.rs:4765:13
  17: roc_load_internal::file::run_task
             at /home/ben/roc/roc-src/crates/compiler/load_internal/src/file.rs:6144:17
  18: worker_task
             at /home/ben/roc/roc-src/crates/compiler/load_internal/src/file.rs:2091:34
  19: roc_load_internal::file::load_multi_threaded::{{closure}}::{{closure}}
             at /home/ben/roc/roc-src/crates/compiler/load_internal/src/file.rs:1831:25
  20: crossbeam_utils::thread::ScopedThreadBuilder::spawn::{{closure}}
             at /home/ben/.cargo/registry/src/index.crates.io-6f17d22bba15001f/crossbeam-utils-0.8.16/src/thread.rs:440:31
  21: core::ops::function::FnOnce::call_once{{vtable.shim}}
             at /rustc/cc66ad468955717ab92600c770da8c1601a4ff33/library/core/src/ops/function.rs:250:5
  22: <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once
             at /rustc/cc66ad468955717ab92600c770da8c1601a4ff33/library/alloc/src/boxed.rs:2007:9
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

[tannerntannern]

I just ran into this issue today, using

roc nightly pre-release, built from commit c95fdd6 on Mi 13 Nov 2024 11:26:07 UTC

Does anyone have context on what this error means? Does it mean importing custom abilities isn't allowed? Does it mean that it's not yet implemented by the compiler? Does it mean the import or ability definition is somehow malformed?

[benplotke]

I don't know what causes the issue, but, as a temporary solution, I got around it by copy pasting the ability directly into the section of code I was using it in. For example

[tannerntannern]

Unfortunately, that doesn't work for my case because I want to expose the ability as part of a package/platform. The ability must be imported.

[benplotke]

Yeah, it's a really basic hole in the functionally. I just got to learn Rust and the Roc compiler and then I can fix it😉. I should probably stop making noise in the comments and wait for someone who actually knows something to chime in